面向等离子体Ti、TiN掺杂钨基复合材料制备及其性能研究

发布时间：2018-11-13 18:10

【摘要】：钨及其合金因其具有高熔点,良好的导热性能,低溅射率等优点被作为ITER中最具潜力的面向等离子体第一壁候选材料。但钨及其合金存在低温脆性、重结晶脆性及辐照脆性等问题,使其在实际应用中受到限制。向钨合金中添加第二相或合金元素是一种提高钨合金综合性能的手段之一。本文采用向钨合金中添加纳米氮化钛(TiN)颗粒和氢化钛(TiH2),通过机械球磨和放电等离子烧结的方法制备了W Ti TiN复合材料,研究了TiN添加量、机械球磨工艺和Ti添加量对W Ti TiN复合材料组织结构和性能影响;同时,对W Ti TiN复合材料抗He~+辐照性能进行研究。主要研究结果如下:(1)采用机械合金化和放电等离子烧结制备W (0.5,1,2,4)wt.%TiN复合材料,TiN颗粒均匀分散在W基体中,对W基体产生弥散强化效果。随着TiN含量增加,晶粒被明显细化,出现穿晶断裂特征以及显微硬度不断增加。W-2wt.%TiN复合材料具有最高致密度(98.73%)和抗拉强度(180MPa)。(2)随着球磨时间的不断增加,所制备的W-15wt.%Ti复合粉末重复着冷焊、断裂、重焊过程,粉末的晶粒尺寸被细化至纳米级别,在80小时球磨后检测到非晶相存在;同时,TiH1.9分解并形成W-Ti固溶体。在烧结之后,随着球磨时间增加,第二相分布更加均匀,并在球磨80小时的样品中观察到W和Ti相的中间区域存在过渡区,其对应于β(Ti,W)相。显微硬度和导热率随着球磨时间延长而增加,80小时球磨粉末制备的复合材料具有最好性能。(3)通过在W TiN复合材料中添加不同含量的Ti元素,复合材料致密度和显微硬度显著提高,晶粒尺寸明显细化至0.51μm。Ti含量为4wt.%时,复合材料性能最佳。在烧结期间,N可能扩散到其它Ti晶格中,从而形成Ti/TiN固溶体。此外,Ti添加改善了复合材料抗He~+辐射性能。没有添加Ti的复合材料,辐照后TiN剥离,在晶界处留下孔洞且引起溅射腐蚀。当Ti含量为8wt.%时,没有观察第二相剥离,仅在W晶粒和富Ti相中都观察到少量密度气泡。
[Abstract]:Tungsten and its alloys are considered as the most promising candidate materials for plasma wall in ITER due to their high melting point, good thermal conductivity and low sputtering rate. However, the low temperature brittleness, recrystallization brittleness and irradiation brittleness of tungsten and its alloys are limited in practical application. Adding the second phase or alloy element to tungsten alloy is one of the ways to improve the comprehensive properties of tungsten alloy. In this paper, W Ti TiN composites were prepared by mechanical ball milling and spark plasma sintering by adding nano-titanium nitride (TiN) particles and titanium hydride (TiH2) into tungsten alloys. The amount of TiN was studied. The effects of mechanical ball milling and Ti addition on the microstructure and properties of W / Ti / TiN composites were investigated. At the same time, the radiation resistance of W Ti / TiN composites to He~ was studied. The main results are as follows: (1) wt.%TiN composites were prepared by mechanical alloying and spark plasma sintering. TiN particles were uniformly dispersed in W matrix, resulting in dispersion strengthening effect on W matrix. With the increase of TiN content, the grain size is obviously refined. The transgranular fracture characteristics and microhardness of W-2wt.%TiN composites are increasing. The W-2wt.%TiN composites have the highest density (98.73%) and tensile strength (180MPa). (2) with the increasing of milling time. The W-15wt.%Ti composite powder was prepared by repeated cold welding, fracture and rewelding. The grain size of the powder was refined to nanometer level, and the amorphous phase was detected after 80 hours ball milling. At the same time, TiH1.9 decomposes and forms W-Ti solid solution. After sintering, the distribution of the second phase became more uniform with the increase of milling time, and the transition region of W and Ti phase was observed in the sample of 80 hours ball milling, which corresponds to 尾 (Ti,W) phase. The microhardness and thermal conductivity increase with the increase of milling time, and the composites prepared by 80 hours ball milling powder have the best properties. (3) by adding different contents of Ti elements into W TiN composites, The densification and microhardness of the composites were significantly increased, and the properties of the composites were the best when the grain size was obviously refined to 4wt.% of 0. 51 渭 m.Ti. During sintering, N may diffuse into other Ti lattice and form Ti/TiN solid solution. In addition, the addition of Ti improves the radiation resistance of composites to He~. The composites without Ti can be stripped off by TiN after irradiation, leaving holes at grain boundaries and causing sputtering corrosion. When the content of Ti is 8 wt.%, the second phase peel is not observed, only a few density bubbles are observed in W grain and rich Ti phase.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33

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